The present disclosure relates to a system and method capable of establishing efficient, robust, multi-hop cooperative routes in communication networks. The techniques disclosed are well-suited for conveying voice, streaming video and other delay-sensitive applications and more specifically in wireless ad hoc networks, by exploiting the concept of barrage relay, thus bypassing the need for carrier sensing and collision avoidance for multiple-access purposes or the creation and use of connectivity tables at each node for routing purposes. In at least one embodiment, these techniques may be used to form a novel, unicast, reactive route-establishment protocol in mobile ad-hoc networks (“MANETs”).
The theory and practice of MANETs has witnessed great interest recently, spurred by applications in the tactical-radio space and related commercial endeavors. However, the development of effective and scalable solutions that satisfy rapid-relaying and routing requirements for streaming and other delay-sensitive, QoS-demanding applications in MANETs has lagged behind, primarily due to the harsh terrestrial propagation, uncertain network topology from node mobility and unreliable links, total lack of infrastructure, large number of hops required for end-to-end connectivity, and so on.
Designed-based problems associated with known MANET techniques include the deficiency in channel accessing and route establishment brought about by the use of classic protocols originally destined for wireless LAN's or cellular networks of the 2nd and 3rd Generation, protocols that simply don't lend themselves to use in the current environment because of their emphasis on process re-initiation at every hop (link). This negative situation has led to calls for new architectures and paradigm shifts in network-protocol-stack design for MANETs [R. Ramanathan, “Challenges: A Radically New Architecture for Next Generation Mobile Ad Hoc Networks,” Proc. ACM/IEEE Int'l Conf. Mobile Comp. and Networking, Cologne, Germany, August 2005, pp. 132-139]. The present disclosure can be viewed as a practical way to affect such a quantum step in designing, implementing, testing and deploying processes and protocols that are particularly well-suited to MANET's and outperform classic solutions by orders of magnitude in latency, throughput, scalability and the like.
As a first step in alleviating these problems and revisiting the MANET networking problem ab initio, U.S. patent application Ser. No. 11/833,113 (discussed above) introduced the concept of barrage relay as a way for multiple network nodes to access the various wireless links in a manner that is delay-efficient, enhances the Signal-to-Noise (SNR) of each packet reception per node and circumvents the problem of packet collisions inherent in classic multiple-access schemes. The techniques of barrage relay are adopted as an underlying mechanism for the current proposition of robust collective route establishment. Thus, the present disclosure results in a substantial modification of the heretofore known, classic PHY transmission/reception mechanisms by exploiting the straightforward and efficient form of autonomously decided, decentralized, minimum-latency transmission schemes and associated diversity-combining reception schemes collectively known as “barrage relay”. It is noted that the “barrage-relay” concept of U.S. patent application Ser. No. 11/833,113 includes and combines the dual notions of “broadcasting by flooding” and of “cooperative diversity” of [S-Y Ni, Y-C Tseng, Y-S Chen and J-P Sheu, “The Broadcast Storm Problem in a Mobile Ad Hoc Network,” MobiCom, Seattle, Wash., 1999] and [D. K. Lee and K. M. Chugg, “Pragmatic Cooperative Diversity Communications,” Proc. IEEE Military Comm. Conf., Washington, D.C., October 2006], respectively, along with unique relaying logic performed by each node. The routing protocol proposed herein harnesses these advantages in a unique way so as to set up any desired cooperative route in a fast, robust and efficient way.
Due to this unique PHY-MAC combination, both U.S. patent application Ser. No. 11/833,113 as well as the present disclosure modify in a substantial way the logic behind the known link-access mechanisms such as Carrier-Sense Multiple Access/Collision Avoidance (CSMA/CA) to be found in, for example, the IEEE 802.11 family of standards (Wi-Fi), where nodes take turns in sending a packet and employ carrier sensing in order to avoid collisions. It does so by exploiting the PHY-layer ability to collect energy from multiple simultaneous (or near-simultaneous) identical packets, thus obviating the need for delaying transmissions and taking turns for fear of collisions at the link layer.
In addition, the present disclosure differs in a substantial way from the heretofore known layer-3 routing schemes collectively known as “ad hoc routing protocols” [M. J. Lee, J. Zheng, X. Hu, H. Juan, C. Zhu, Y. Liu, J. S. Yoon, and T. N. Saadawi, “A New Taxonomy for Routing Algorithms for Wireless Mobile Ad Hoc Networks: The Component Approach,” IEEE Communications Magazine, vol. 46, pp. 116-123, November 2006] (a classic representative of which is, for instance, the Ad-hoc On-demand Distance Vector—AODV protocol for on-demand routing protocols presented at the MANET working group) by obviating the need to form connectivity tables at each node and thus greatly reducing the concomitant expenditure of network capacity in control signaling for forming and maintaining such.
The present disclosure thus effectively merges the PHY-MAC layer properties of autonomous transmission and cooperative-diversity reception inherent in the barrage-relay concept of U.S. patent application Ser. No. 11/833,113, along with a novel layer-2 routing (collective path-setting) mechanism presented herein, to arrive at an effective, reactive (on-demand), cross-layer optimized method for a joint PHY-MAC-routing protocol creation.